Precision measurement of the 6He half-life and the weak axial current in nuclei.

Studies of 6He beta decay along with tritium can play an important role in testing ab initio nuclear wave-function calculations and may allow for fixing low-energy constants in effective-field theories. Here, we present an improved determination of the 6He half-life to a relative precision of 3×10(-4). Our value of 806.89±0.11(stat)(-0.19syst)(+0.23)  ms resolves a major discrepancy between previous measurements. Calculating the statistical rate function we determined the ft value to be 803.04(-0.23)(+0.26)  s. The extracted Gamow-Teller matrix element agrees within a few percent with ab initio calculations.